Katie, I'm not a singer but I am a former musician. About a year or two out from surgery and rads, over about a month I suddenly GAINED a perfect fourth at the bottom of my vocal range. Just like that I went from being a normal baritone to a bass. Not that you'd want to hear me sing of course.
My point though is that we're all so different that it's virtually impossible to predict what will happen.
Also, although I didn't have tongue surgery, I found that my taste gradually did come back, as did much of my saliva. Taste is still and likely never will be 100% because of surgical nerve damage, but it's something I can live with.
So please hang in there. Getting more opinions, especially from people at the great hospitals you mention, can only hope.
Keep us posted please.